The present invention relates to a system for storing heat derived from a plurality of independent sources. Such systems generally are not new; however prior art systems of this type suffer from a number of disadvantages. For example, one prior art system requires a storage tank with a multiplicity of heat exchangers which are inserted into a storage vessel. This results in a cumbersome assembly which requires a substantial amount of heat transfer surface for each heat exchanger because of the fact that the water in the storage vessel is practically stagnant. As a result, heat transfer from the heat exchanger to the storage fluid is slow and inefficient.